<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        div{
            width: 100%;
            height: 400px;
            background-color: orange;
        }
    </style>
</head>
<body>
<div></div>
</body>
</html>